Answer: $20.5
Step-by-step explanation:
Let x denotes the amount for total bill.
We are given that , Sierra left $4.50 as a tip for a waiter.
This was 18% of the bill before the tip.
We can write 18% = 0.18. [To convert percent into decimal we divide it by 100.]
Then, the tip amount = 0.18 x Total bill
So, the total bill amount = $25
Hence, her total bill before the tip= Total bill amount - Tip amount
= $25- $4.50=$20.5
Thus ,her total bill before the tip= $20.5